Nanofibrillar cellulose refers to isolated cellulose microfibrils or microfibril bundles derived from cellulose raw material. Nanofibrillar cellulose (NFC), which is also known as microfibrillar cellulose (MFC), and by other related names, is a natural polymer that is abundant in nature. Generally, nanofibrillar cellulose has high aspect ratio and the fibril length can be up to several microns.
Traditionally, nanofibrillar cellulose production techniques are based on grinding or homogenizing of aqueous dispersion of pulp fibers. The concentration of nanofibrillar cellulose in dispersions is typically low, usually around 1-5%.
The production of nanofibrillar cellulose by fibrillating cellulose fibers into nano-scale elements requires intensive mechanical treatment. In order to produce purified cellulose or reduce energy demand, chemical treatment or enzymatic treatment may be applied prior or posterior to mechanical fibrillation, for breaking the fibrils and lowering the aspect ratio. These processes are often industrially tedious and expensive.
On the other hand, through the mechanical fibrillating process, the viscosity of the pulp fiber suspension increases during the process. Therefore, after the grinding or homogenization process, the obtained nanofibrillar cellulose material is a dilute viscoelastic hydrogel. However, for certain applications, a challenge associated with using NFC/MFC is the high viscosity in aqueous state.
Therefore, there is a need of easy-to-produce and cost-effective nanofibrillar cellulose having low viscosity and still preserving desirable properties of fibril cellulose.